The present invention relates to multi-track read heads for accessing magnetic media.
Multi-track magnetic media access heads, such as tape heads, typically include one or more read modules. Each read module has a plurality of read elements for simultaneously reading data tracks written on the magnetic media. The need for greater areal information density stored on magnetic media has resulted in a narrowing of data track widths, a decrease in spacing between data tracks, and an increase in the linear density of information recorded on each track. These increases in areal information density require improvements in the design of read modules.
Read elements may be inductive or magnetoresistive (MR). MR read sensors may be based on the anisotropic or giant magnetoresistance effects. Anisotropic MR sensors may use a single element or a coupled element structure. An example of a coupled element MR read sensor is provided in U.S. patent application Ser. No. 09/170,330, titled xe2x80x9cDual Element Magnetoresistive Read Head With Integral Element Stabilizationxe2x80x9d by B. Engel et al., which is herein incorporated by reference. Regardless of the sensor type, read element resolution may be increased by placing magnetic shields on either side of the read element in the direction of tape travel. A magnetically insulative material is placed in the read gap between the read element and each shield. The distance between the read element and the shield, known as the read gap distance, is based on the type of read element, geometry of the read element, type of magnetic media used, and the format of data written onto data tracks. Having symmetric read gap distances is important in coupled element MR sensors, where the read gap distances affect biasing between the element pair.
Two types of shields are used, thin film shields and mechanical closures. Mechanically closed shields are typically a magnetically permeable slab, such as ferrite, which is clamped and glued into place on top of the read element film stack. Mechanical closures are effective and simple to manufacture. However, several difficulties arise. First, the read gap distance is controlled by the ability to correctly attach the closure. Any variation in read gap distance, due to for instance contamination of the closure or substrate, variation in clamping pressure, or deformation of the closure or substrate leading to non-parallelism of the read gap, will detrimentally affect the functionality of the read head. Second, since the closure extends across all read elements in the multi-track module, crosstalk may develop between read elements. Third, mechanically clamping the closure places stress on the read module, which may have an adverse affect on read module operation. Fourth, voids may form between the closure and the read element substrate. These voids may collect debris which may affect the magnetic properties of the tape head and may create electrical shorts.
An alternative to a mechanically closed shield is a thin film shield. Thin film shields are formed by depositing one or more magnetically permeable layers over the read elements. Due to the accuracy of thin film processing, thin film shields produce read gap distances with smaller tolerances than mechanically closed shields. However, the processing steps for a thin film shield module can be complex with the potential for yield reduction in multi-track tape modules.
What is needed is a read module with accurately controlled read gap distances between read elements and shields. The read module should have good wear properties, should not capture debris, and should minimize crosstalk between read elements. A method of easily making such a read module is also desired.
It is an object of the present invention to provide a multi-track read module with accurate gap distances between read elements and shielding material.
It is another object of the present invention to provide a multi-track read module that is easy to manufacture.
It is still another object of the present invention to provide a read module that minimizes crosstalk between read elements.
It is yet another object of the present invention to provide a multi-track read module with good wear properties.
It is a further object of the present invention to provide a multi-track read module that will not capture debris.
In carrying out the above objects and other objects and features of the present invention, a read module having a plurality of read elements is provided. The read module includes a bottom shield layer. A plurality of read elements is formed on the bottom shield layer. A plurality of top shields is formed as a top shield layer. Each top shield is deposited over one read element. Each top shield is physically isolated from any other top shield and from the bottom shield layer. An insulative spacer layer is deposited between the plurality of top shields. A closure is fixed to the spacer layer.
In an embodiment of the present invention, the spacer layer is thicker than the top shield layer. In a refinement, the spacer layer is approximately ten percent thicker than the top shield layer, thereby providing mechanical support for the closure.
In another embodiment of the present invention, the closure is mechanically attached and glued onto the spacer layer.
A method for manufacturing a read module having a plurality of read elements is also provided. A bottom shield layer is formed. The plurality of read elements is formed on the bottom shield layer. A plurality of top shields is deposited as a top shield layer on the read elements. Each top shield is physically separated from an adjacent top shield by a gap. An insulative spacer layer is deposited on top of the shield layer. The spacer layer substantially fills the gaps between top shields. A closure is bonded to the spacer layer.
The above objects and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.